A MEP-701a IS a MEP-016b in an ASK housing, for some reason they just decided to give it another model number unlike the MEP-002a and MEP-003a with ASK perhaps because the MEP-701a ASK upgrade was a depot job and the MEP-002a/003a was field installable.
A quick rundown on the MEP-016 model family, all share the same 3600 rpm 3KW generator end:
MEP-016a and MEP-016c have gasoline pull start engines very similar to each other
MEP-016b have a 1 cylinder Onan diesel, very different from the A/C, different frame, electric start, etc. same generator end
MEP-016D Old MEP-016a/c models retrofitted with a Yanmar L70 diesel engine, retrofit program began around the year 2001
MEP-016E MEP-016b (may also be MEP-701a) retrofitted with a Yanmar L100 diesel engine
Note both the D and E revisions may still have the orginal data plate claiming to be a A/C or B and not the revised data plate
Ike
p.s. the MEP-016a/c seem to mostly be built in the 1970's, the MEP-016b seems to be mostly from the late 1980's to early 1990's (mine was built in 1988 ), and the Yanmar life extension retrofits date from about 2001